Screw jack



J. C. KOPF.

SCREW JACK.

APPLICATION 'nuzo Aue.2. 1920.

1,413,229. Patented Apr. 18, 1922.

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Jam 0. Kori, on BELLEVUE Boaonerr, rENNsYLv NIA, ASSIGNOB TO THE DUFF I MANUFACTURING COMPANY, or PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

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Specification of Letters Patent. Patented 18, 1922.

Application filed August 2, 1920. Serial No. 400,802.

To all whom it may concern:

Be it known that 1, JOHN C. KoPF, a citizen of the United States, and resident of the borough of Bellevue, in the county offAllegheny and State of Pennsylvania, have in vented a new and useful Screw Jack, of which the following is a specification.

The invention relates to screw-jacks of the kind in which a hollow cylindrical acking member is slidably guided in a bearing in the top of an enclosing base frame, on the bottom of which the lifting screw is rotatably supported, and comprises an improved and inexpensive construction whereby the bearing is protected from dirt and grit, while being utilized for a positive stop to prevent over-lifting.

In the accompanying drawings forming a part hereof:

Figure 1 is a vertical section of a journalbox jack embodying the invention, showing the jacking member in its lowered position;

Fig. 2 is a vertical section at'right angles to Fig. 1 through the upper part of theframe, showing the jacking member, inelevation, in fully raised position; I Flg. 8 isa cross-section. on the l1ne-3-3 I of Fig. 2; and

Fig. 4 is a bottom plan of the jacking member and nut.

The hollow frame or bell is designated 1; and 2 is its inwardly projecting top bearing;

, A hollow cylindrical jacking member 3 slides in this bearing, wherein it is prevented from turning by a key 4 in the bearing cooperating with a vertical slot 5 in the side of the jacking member.

The jacking member is actuated by a vertical screw 6, rising from the base, on which it is rotatably supported by a ball-bearing 7. The screw in turn is operated from a horizontal operating shaft 8 journaled in-a bearing 9 in the frame, and having a bevel pinion 10 on its inner end, meshing a bevel gear 11 keyed to the plain lower end 12 of the screw.-

The screw extends upward within the jacking member, through a nut 13, which is inserted in a cavity in the bottom of the member, against an internal supporting the bottom" ledge of the top bearing and absolutely prevents further movement, the strain, however, falling on the separate nut, the jacking member being merely sustained by the arrested nut.

The combined member has a second enlargement, consisting of a head 16 which laterally overhangs the top opening of the bearing 2 sufficiently to close the same against admission of grit when the jack is in its normal Or retracted condition, at which time a journal-box jack, for example, may be lying with the coal in the tender, or in some other equally dirty spot. Such head can be quite small and made to fit the mouth of the bearing; and the two parts, namely the nut and jacking member, with their ininto the lower end of the member, where it i is held-against rotation by a pin'l'l'.

What is claimed as new is: I

1. jack comprising a hollow base frame having a bearing at its upper end, a lifting screw rotatably supported on the bottom of said frame, a hollow cylindrical jacking member slidably guided in said bearing and formed at the top with an enlargement constituting a bearing closure, and a nut inserted into the lower end of the jacking member and formed with a stop to coact with the bottom of the-bearing. I

2. A jack comprising a hollow base frame having a hearing at its upper end, a lifting screw rotatably supported on the bottom of said frame, a hollow V cylindrical jacking member slidably guided in said bearing and formed at the top with an enlargement 0011- stituting a bearingclosure, and a nut in-- sorted into the ,lower' end of the jacking member, the lower end of said nut projecting below the jacking member and extending laterally beyond the periphery thereof in the form of a stop flange.

. 3. A jack comprising a hollow base frame having a bearing at its upper end, a lifting thelower end of said nut projecting below the jacking member andextending laterally beyond the periphery thereof in the form of 21,9501; flange, said Stop flange being 10 'o'niitted at one sick, and means locking the nut in position in the jacking-member.

JOHN G. K0191: 

